The entire disclosure of Japanese Patent Application No. 2001-234625 filed on Aug. 2, 2001 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.
1. Field of the Invention
This invention relates to a roll changing apparatus and a roll changing method for a rolling mill in rolling equipment.
2. Description of the Related Art
There have been roll changing apparatuses for four-high rolling mills as shown, for example, in FIGS. 14 to 18.
FIG. 14 shows a roll changing apparatus called a C-hook system. When upper and lower work rolls 100 are to be changed, for example, a lower end receiving portion 103 of a C-hook 102 exclusive to work rolls, which has been suspended from a hook 101 of a crane, is engaged with the shaft ends of the upper and lower work rolls 100 within a rolling mill stand 104. Then, the upper and lower work rolls (assembly) 100 are slightly lifted by handling of the crane to disconnect them from a lower backup roll (assembly) 105. (At this time, an upper backup roll (assembly) 105 has been slightly raised.) Then, the upper and lower work rolls 100 are pulled out into a pit P present before the rolling mill. Then, the upper and lower work rolls 100 are transported by the crane to a predetermined site of replacement, where they are changed to new upper and lower work rolls (assembly) 100. Changing of the upper and lower backup rolls 105 is also performed in a similar manner using a C-hook exclusive to backup rolls.
FIG. 15 shows a roll changing apparatus called a cluster system. When upper and lower work rolls 100 are to be changed, for example, a pit P before a rolling mill is opened, and the upper and lower work rolls (assembly) 100 are stacked on and supported by a lower backup roll (assembly) 105 supported on a sled 106 in a rolling mill stand 104. (At this time, an upper backup roll (assembly) 105 has been slightly raised.) Then, the sled 106 is moved on a base 108 by a hydraulic cylinder 107 to push out the upper and lower work rolls (assembly) 100 into the pit P before the rolling mill. Then, the upper and lower work rolls (assembly) 100 are changed to new upper and lower work rolls (assembly) 100 by a crane operation. After changing, the new upper and lower work rolls (assembly) 100 are set into the rolling mill stand 104 by the same procedure performed in reverse. Changing of the upper and lower backup rolls 105 is performed, in the case of the lower backup roll (assembly) 105, by exactly the same procedure as that for the upper and lower work rolls (assembly) 100, or in the case of the upper backup roll (assembly) 105, by a similar procedure using a stool (not shown; a so-called dummy for the upper and lower work rolls (assembly) 100) and placing the upper backup roll (assembly) 105 on the stool.
FIGS. 16 and 17 show a roll changing apparatus called a side shift system. In detail, a four-high rolling mill 50 on a rolling line has a rolling mill stand 51, upper and lower work rolls 52 as a pair, and upper and lower backup rolls 53 as a pair. In the drawings, Ds denotes a drive side of the rolling line, while Ws denotes a work side of the rolling line.
The above roll changing apparatus has a work roll pushing-out/pulling-in pusher 54 disposed on the drive side Ds of the rolling line, and a backup roll pulling-out/pushing-in hydraulic cylinder 55 disposed on the work side Ws of the rolling line. In FIG. 16, 54a denotes a connecting fitting at the tip of the pusher 54, 54b denotes a connecting fitting at the end of a roll chock 52a of the work roll 52 opposed to the pusher tip, 55a denotes a connecting fitting at the tip of the hydraulic cylinder 55, and 55b denotes a connecting fitting at the end of a roll chock 53a of the lower backup roll 53 opposed to the tip of the hydraulic cylinder 55.
Changing of the work rolls 52 is performed by a method which comprises relieving the upper backup roll 53 and the upper work roll 52 to ascending positions, raising the lower work roll 52 to a roll change height, pushing out the lower work roll 52 over a small distance by the pusher 54, lowering the upper work roll 52 onto the lower work roll 52 to stack them in a roll change posture, pushing out the upper and lower work roll assembly onto a shift table 56 by forward or extended driving of the pusher 54, replacing this old work roll assembly with a new work roll assembly by a shift or a shifting movement of the shift table 56 caused by a shifting cylinder 64, and pulling the new work roll assembly into the rolling stand 51. At this time, the work roll assembly is adapted to act such that wheels 57 mounted on the roll chocks 52a of the lower work roll 52 move on up-and-down rails 58a in the rolling mill stand 51 and on rails 58b on the shift table 56.
Changing of the backup rolls 53 is performed after pushing the work roll assembly out of the rolling mill stand 51 onto the shift table 56, and temporarily removing the work roll assembly, the shift table 56, a detachable girder 62a, and a detachable rail 63a located before the rolling mill. That is, changing of the backup rolls 53 is performed in the following manner: The connecting fitting 55a of the hydraulic cylinder 55 is coupled to the connecting fitting 55b on the side of the lower backup roll 53, and the lower backup roll 53 is pulled out to the work side Ws of the rolling line. At the pullout position, an upper backup roll-loading (roll changing) stool 59 is mounted on the lower backup roll 53, and they are pushed into the rolling mill stand 51. The upper backup roll 53 is lowered, and loaded on the stool 59, whereafter the upper and lower backup rolls 53 are pulled out to the work side Ws by the hydraulic cylinder 55. At the pullout position, the upper backup roll 53 is replaced with a new upper backup roll 53. The new upper backup roll 53 is pushed into the rolling mill stand 51, and set at a predetermined height position. The lower backup roll 53 loaded only with the stool 59 is pulled out to the work side Ws, where the stool 59 is detached, and the lower backup roll 53 is replaced with a new lower backup roll 53. The new lower backup roll 53 is pushed into the rolling mill stand 51, and set in place.
At this time, the weight of the assembly including the stool 59 and the upper and lower backup rolls 53, generally, moves slidingly on a slide base 61a in the stand 51 and on a slide base 61b on the work side Ws via slide members 60 provided at the roll chocks 53a of the lower backup roll 53.
When roll changing is performed by the above-described C-hook system or cluster system, a changing operation by handling of the crane accounts for most of this task, and requires labor and time. In recent years, therefore, a demand has risen for modifying equipment in order to switch to the side shift system that minimizes a changing operation by handling of the crane and requires minimal downtime for the rolling line.
With the aforementioned conventional side shift type roll changing apparatus, however, large drive devices (pusher 54 and hydraulic cylinder 55) for bringing the work rolls and the backup rolls into and out of the rolling mill stand are provided separately. Thus, the fixtures cost is high, and installation (accommodation) spaces for them have to be secured.
Furthermore, the shifting girders and rails in an upper part of the backup roll pulling-out pit need to have a separable, detachable rail structure for each rolling mill. Thus, the structure is complicated and upsized, and the cost and construction time involved in modification are increased. Incidentally, the detachable girder 62a (and rail 63a) has opposite end portions carried by the ends of fixed girders 62 (and rails 63), as shown in FIGS. 18(a) to 18(c), to take charge of the work roll weight of about 20 to 30 tons per girder (rail). To maintain the strength of the carried portion and prevent warpage of the rail, the cross section of the girder 62a (and the rail 63a) needs to be I-shaped, and needs to have predetermined dimensions in the height direction (i.e., h1 and h2). The dimension H on the fixed side depends on h1, so that as h1 increases, H also increases. In the absence of the detachable girder 62a (and rail 63a), on the other hand, the magnitude of H can be decreased. In other words, if it is necessary to mount the fixed girder 62 (and rail 63) into the channel-shaped pit, the depth of the pit can be made small.
The present invention has been proposed in consideration of the above problems with the earlier technologies. It is the object of the invention to provide a roll changing apparatus for a rolling mill which can be modified into a side shift type roll changing apparatus with ease, at a low cost, and in a short time.
A first aspect of the present invention, for attaining the above object, is a roll changing apparatus for a rolling mill, comprising:
rails, provided in a stand of the rolling mill and on a work side of the rolling mill, for incoming and outgoing of a work roll assembly and a backup roll assembly; and
a pusher, provided on a drive side or the work side of the rolling mill, for roll admission and withdrawal for both of work rolls and backup rolls.
According to this aspect, changing of the work rolls and changing of the backup rolls can be performed by the single pusher, and the conventional hydraulic cylinder for the backup rolls, for example, can be omitted. Thus, the fixtures cost can be reduced markedly, and the range of formation of deep foundations can be decreased to cut down on the construction cost for foundations. Particularly in the case of modifying the existing equipment, the conventional backup roll pulling-out pit portion can be effectively used, unchanged, for modification. This results in marked shortening of the construction period and a marked decrease in the cost of modifying the foundations.
In the roll changing apparatus for a rolling mill, a roll changing stool to be assembled to the backup roll assembly may be provided with wheels and a connecting fitting for connection with the pusher so that the roll changing stool can be moved on the rails for incoming and outgoing of the work roll assembly by driving of the pusher.
According to the above feature, the pushing-out/pulling-in procedure by the pusher during backup roll changing is decreased by one reciprocation. Thus, a saving in labor is achieved.
In the roll changing apparatus for a rolling mill, lower backup roll chocks of the rolling mill may be provided with wheels so that the backup roll assembly can be moved by the wheels on the rails for incoming and outgoing of the backup roll assembly.
According to the above feature, movement of the backup roll assembly can be made smoothly compared with the use of the slide members.
In the roll changing apparatus for a rolling mill, the rails for incoming and outgoing of the backup roll assembly in the rolling mill stand can be raised and lowered by hoisting and lowering means, a lower backup roll chock may be equipped with a connecting fitting which can be connected to a drive end of the pusher at a raised position of the lower backup roll chock, and fixed rails for incoming and outgoing of the backup roll assembly on the work side may be provided at a height consistent with a raised height of the rails for incoming and outgoing of the backup roll assembly in the rolling mill stand.
According to the above feature, the same actions and effects as in the first aspect of the invention can be obtained, and the conventional roll changing stool can be used.
In the roll changing apparatus for a rolling mill, the lower backup roll chock may be movable on the rails and fixed rails for incoming and outgoing of the backup roll assembly via wheels.
According to the above feature, movement of the backup roll assembly can be made smoothly compared with the use of the slide members.
A second aspect of the invention is a roll changing method for a rolling mill, comprising:
actuating a work roll assembly and a backup roll assembly by a single pusher, provided on a drive side or a work side of the rolling mill, for roll admission and withdrawal in performing a roll changing operation from the work side of the rolling mill, whereby the work roll assembly and the backup roll assembly are admitted into or withdrawn from a rolling mill stand.
According to this aspect, changing of the work rolls and changing of the backup rolls can be performed by the single pusher, and the conventional hydraulic cylinder for the backup rolls, for example, can be omitted. Thus, the fixtures cost can be reduced markedly, and the range of formation of deep foundations can be decreased to cut down on the construction cost for foundations. Particularly in the case of modifying the existing equipment, the conventional backup roll pulling-out pit portion can be effectively used, unchanged, for modification. This results in marked shortening of the construction period and a marked decrease in the cost of modifying the foundations.
A third aspect of the invention is a roll changing apparatus for a rolling mill, the roll changing apparatus being a side shift roll changing apparatus installed on a work side of the rolling mill and comprising:
a shift table capable of aligning with a roll axis line position of the rolling mill; and
shifting rails provided on a floor and a bottom of a backup roll pulling-out pit dividedly in a shifting direction in order to support the shift table at a required height, and wherein
the shift table is shifted nearly horizontally in the pit by drive means while extending over a floor rail portion and a pit bottom rail portion.
According to the above aspect, the shift rail structure can be simplified and downsized, so that the expenses and construction period for modification can be reduced, and labor for maintenance and administration can be decreased. In changing the backup rolls, moreover, the conventional operation for mounting and dismounting the rails exclusive to the side shift trolley is unnecessary, markedly shortening the time for the changing operation.
The roll changing apparatus for a rolling mill may further include legs extending downwardly from an end portion of the shift table, which faces the pit, nearly perpendicularly into the pit, and lower end portions of the legs may be shiftable on the pit bottom rail portion while maintaining the shift table nearly horizontally.
According to this feature, the first shift table can smoothly shift on the shifting rails provided with a step.
In the roll changing apparatus for a rolling mill, discontinuous backup roll pulling-out rails, which do not cross the pit bottom rail portion, may be provided at the bottom of the pit so as to be capable of pulling out backup rolls to a higher position than the pit bottom rail portion.
According to this feature, the backup rolls can be smoothly pulled out without interference from the pit bottom rail portion.
In the roll changing apparatus for a rolling mill, a pair of wheels may be provided on a lower portion of a roll chock of the backup roll with a spacing greater than a lengthwise dimension of a discontinuous portion of the backup roll pulling-out rails.
According to this feature, the backup rolls can be smoothly rolled on the discontinuous rails, and pulled out of or pushed into the rolling mill stand.
In the roll changing apparatus for a rolling mill, a slide member of a length larger than a lengthwise dimension of a discontinuous portion of the backup roll pulling-out rails may be provided on a lower portion of a roll chock of the backup roll.
According to this feature, the backup rolls can be smoothly shifted on the discontinuous rails, and pulled out of or pushed into the rolling mill stand.
The roll changing apparatus for a rolling mill may further include a second shift table connected to the shift table, and the second shift table may shift such that one end thereof is detachably connected to and supported by an end portion of the first shift table facing the pit, and the other end thereof is supported on the floor rail portion on a side opposite to the first shift table, with the pit being located between the first shift table and the floor rail portion, and the second shift table may be supported on the floor rail portion at opposite end portions thereof in a state in which the first shift table has stopped at the roll axis line position of the rolling mill.
According to the this feature, the same actions and effects as in the third aspect of the invention are obtained, and the two shift tables are alternately aligned with and stopped at the position of the roll axis line of the rolling mill, achieving rapidity of the changing operation.
A fourth aspect of the invention is a roll changing method for a rolling mill, used in operating a roll changing apparatus of a side shift type installed on a work side of the rolling mill and having a shift table to be aligned with a roll axis line position of the rolling mill, comprising:
shifting the shift table by moving the shift table on shifting rails provided on a floor and a bottom of a backup roll pulling-out pit dividedly in a shifting direction.
According to the above aspect, the shift rail structure can be simplified and downsized, so that the expenses and construction period for modification can be reduced, and labor for maintenance and administration can be decreased. In changing the backup rolls, moreover, the conventional operation for mounting and dismounting the rails exclusive to the side shift trolley is unnecessary, markedly shortening the time for the changing operation.
A fifth aspect of the invention is a roll changing apparatus of a side shift type for a rolling mill, installed on a work side of the rolling mill and comprising:
rails, provided in a stand of the rolling mill and on a work side of the rolling mill, for incoming and outgoing of a work roll assembly and a backup roll assembly;
a pusher, provided on a drive side or the work side of the rolling mill, for roll admission and withdrawal for both of work rolls and backup rolls;
a shift table capable of aligning with a roll axis line position of the rolling mill; and
shifting rails provided on a floor and a bottom of a backup roll pulling-out pit dividedly in a shifting direction in order to support the shift table at a required height, and wherein
the shift table is shifted nearly horizontally in the pit by drive means while extending over a floor rail portion and a pit bottom rail portion.
According to this feature, the conventional hydraulic cylinder for the backup rolls can be omitted. Thus, the fixtures cost can be reduced markedly, and it becomes unnecessary to construct foundations, such as the pit, which are formed for accommodating the hydraulic cylinder. In addition, the side shifting rail structure of the backup roll pulling-out pit has been changed from a detachably constructed system to a fixedly laid system. Thus, the structure can be simplified and downsized. Particularly when the channel-shaped pit is formed, its depth can be decreased. Consequently, the expenses and construction period for modification can be markedly reduced.
A sixth aspect of the invention is a roll changing method for a rolling mill, used in operating a roll changing apparatus of a side shift type installed on a work side of the rolling mill and having a shift table to be aligned with a roll axis line position of the rolling mill, comprising:
actuating a work roll assembly and a backup roll assembly by a single pusher, provided on a drive side or the work side of the rolling mill, for roll admission and withdrawal, whereby the work roll assembly and the backup roll assembly are admitted into or withdrawn from a rolling mill stand, and
shifting the shift table by moving the shift table on shifting rails provided on a floor and a bottom of a backup roll pulling-out pit dividedly in a shifting direction.
According to this feature, the same actions and effects as in the fifth aspect of the invention can be obtained.